Name: how mass differs from weight
Uploaded: 2023-09-22T11:49:39.000Z
Duration: 1 min 19 s
Channel: JoVE

La massa di un oggetto è una misura della quantità di materia che contiene e dipende dal numero di atomi in esso contenuti.
Il suo peso è la forza gravitazionale che agisce su di esso da un oggetto più grande, come la Terra o la Luna, a seconda di quale sia il più vicino ad esso.
Poiché la quantità di materia non cambia in risposta alla forza applicata, la massa dell'oggetto rimane costante.
Tuttavia, il suo peso dipende dalla sua posizione. Un oggetto sulla Terra pesa in modo diverso da quello su Marte o sulla Luna, ma la sua massa rimane la stessa. La variazione di peso è dovuta alla differenza di accelerazione dovuta alla gravità che agisce su di essa.
La massa non può mai essere zero, ma il peso diventa zero quando la forza gravitazionale non agisce su di esso. Usando questa osservazione e la seconda legge di Newton, un oggetto di massa m pesa m volte il vettore g.
Vale a dire, maggiore è la massa di un oggetto, maggiore è il suo peso. La massa è una quantità scalare, ma il peso è un vettore diretto verso il centro della Terra.

massa e peso

Massa e peso sono spesso usati in modo intercambiabile nelle conversazioni quotidiane. Per esempio, spesso le cartelle cliniche riportano il nostro peso in chilogrammi e mai, come sarebbe corretto, in Newton. In fisica, tuttavia, c'è una distinzione fondamentale. Il peso è l'attrazione della Terra su un oggetto. Esso dipende dalla distanza dal centro della Terra. Il peso cambia drasticamente se lasciamo la superficie della Terra, diversamente dalla massa, la quale non cambia a seconda del luogo. Per esempio, sulla Luna, l'accelerazione causata dalla gravità è di solo 1,67 m/s2 se confrontata con i 9,8 m/s2 sulla Terra. Inoltre, sulla Terra una massa di 1,0 kg ha un peso di 9,8 N, ma sulla Luna è di solo 1,7 N. Comunque, la massa di un oggetto è la stessa sulla superficie della Terra, in orbita o sulla superficie della Luna.

Quando un oggetto viene fatto cadere, esso accelera verso il centro della Terra. La seconda legge di Newton afferma che una forza netta su un oggetto è responsabile della sua accelerazione. Se la resistenza dell'aria è trascurabile, la forza netta che agisce su un oggetto mentre cade è uguale alla forza di gravità, comunemente conosciuta come il suo peso, o la forza causata dalla gravità che agisce sulla massa di un oggetto "m".

Notiamo che, anche se sono strettamente correlati, il peso e la massa sono grandezze fisiche diverse. La massa è una proprietà intrinseca di un oggetto ed è una quantità di materia. Si è tentati di equiparare la massa al peso perché la maggior parte dei nostri esempi ha luogo sulla Terra, dove il peso di un oggetto varia minimamente con la posizione dell'oggetto sulla Terra. Inoltre, è difficile contare e identificare tutti gli atomi e le molecole in un oggetto, perciò la massa è raramente determinata in questo modo.

Questo testo è stato tratto e adattato da <a href="https://openstax.org/books/university-physics-volume-1/pages/5-4-mass-and-weight">Openstax, University Physics Volume 1, Section 5.4: Mass and Weight.</a>

Massa e peso

Massa e peso sono spesso usati in modo intercambiabile nelle conversazioni quotidiane. Ad esempio, le cartelle cliniche spesso mostrano il nostro peso in chilogrammi, ma mai ...

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Mass and Weight

how mass differs from weight

Mass and weight are related, but they are not the same. Mass is the amount of matter in an object. Weight is the force of gravity acting on that object.

This difference matters because mass stays the same even when gravity changes. Weight can change if the gravitational pull changes. A person or object therefore has the same mass, but not always the same weight.

The terms are often used in everyday speech as if they mean the same thing. In physics, they describe two different ideas. Understanding both helps students read science problems and compare objects more accurately.

How Mass Differs from Weight

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Learn how mass and weight are different in physics. This K12 science video explains mass as matter and weight as the force of gravity on an object.

How Mass Differs from Weight | JoVE K12

JoVE Core Mechanical Engineering offers concise, easy-to-understand animated videos covering key topics such as equilibrium, forces, truss analysis, and structural mechanics. Explore their real-world applications, and witness these concepts in action through scientist-led experiments.

mechanical engineering

How Mass Differs from Weight

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